In addition, among patients with RH, individuals whose hypertension is uncontrolled on 3 or more medications (uRH) are at increased risk of ESRD and cerebrovascular accident (CVA) compared with those whose resistant hypertension is controlled with 4 or more drugs (cRH).

In a 5-year retrospective cohort study, John J. Sim, MD, of Kaiser Permanente Los Angeles Medical Center, and collaborators compared with risk of ESRD, CVA, ischemic heart event (IHE), congestive heart failure (CHF), and all-cause mortality among 470,386 individuals with resistant and non-resistant hypertension (non-RH). The researchers subcategorized the 60,327 individuals with resistant hypertension into 2 groups: 23,104 patients with cRH and 37,223 with uRH. The study population consisted of members of the Kaiser Permanente Southern California (KPSC) health system.

Compared with non-RH patients, the cRH and uRH patients had a 32%, 24%, 46%, 14%, and 6% increased risk for ESRD, IHE, CHF, CVA, and all-cause mortality, respectively, in adjusted analyses, Dr. Sim's team reported in Kidney International (2015;88:622-632). Compared with cRH patients, uRH patients had a 25% and 23% increased risk of ESRD and CVA, respectively.

Additionally, results showed that men and Hispanics had an increased risk for ESRD in all 3 cohorts.

“Our findings underscore the hypothesis that resistant hypertension has a more adverse physiology and deserves better understanding in order to better manage this population,” the authors concluded.

The researchers noted that the observations from their study were derived from a single integrated health system in which all hypertensive patients received care in a comparable treatment environment, including medications. KPSC has a relatively homogeneous hypertension management program. “Nevertheless, the comparative outcomes reported represent findings from a real-world clinical practice environment in which decisions are made based on provider perceptions,” the authors wrote. “We also feel that the mixture, size, diversity, and length of follow-up in our cohort is a strength of our study.”

Dr. Sim and his colleagues also acknowledged potential study limitations. For example, they noted that they identified the study cohort from a 2-year window and followed up patients for as long as 5 years. In contrast to the real-world phenomenon where blood pressures vary over time, “we somewhat arbitrarily” identified a cohort as having resistant hypertension. The assumption was the once individuals were identified as having resistant hypertension, they would continue to have it throughout the observation period, they stated. “Conversely, those with non-RH may have gone on to develop resistant hypertension.” The investigators also pointed out that they did not have information on the duration of hypertension.